quantitative analyses of periphyton biomass and ... - SUNY Oneonta

plates, each 5 cm x 10 cm and having a designated area of 45 cm 2 on each
side, were fed onto the plastic coated coat hanger wire. Plastic tubing, with a
larger diameter, was cut into five pieces. Each piece fit tightly between each
plate and between the blocks of wood and the nearest plate. This procedure
was necessary to prevent the plates from scraping against each other when the
water was turbulent.
Each artificial substrate holder was piaced in an area of the stream that
was deep enough to completely cover the plates and where the plates could
receive as much incident light as possible. The holders were oriented so that
the plates were parallel to the current. When necessary, heavy rocks were put
near the sides of the holders for stabilization in faster currents. During the
winter months, bricks were affixed to the bottom of the slate base to add weight
to prevent the holders from being carried downstream by rapid currents and ice
movements. This technique was not always successful.
Collection, Preparation, and Analysis of Samples
After 28 days of incubation in the streams, the plexiglass plates were
removed and replaced with clean ones. After removal, the plates were placed
in individual jars with stream water. As soon as the plates were brought back to
the lab the periphyton was scraped off and prepared for chlorophyll a and ash­
free dry weight (AFDW) analysis.
For chlorophyll a analysis, periphyton samples were ·filtered using glass
fiber filters (APHA 1989). The filters were then placed in vials and frozen until
analysis could be performed. The periphyton samples for AFDW analysis were
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